Aircraft gyrohorizon indicator with signal lamp positional attitude indicating means

ABSTRACT

A combination gyrohorizon instrument for aircraft which visually indicates in addition to the dial display presentation of the instrument, by means of signal lamps appropriately placed with respect to the instrument dial, departures from straight and level flight that exceed reasonable limits of pitch and bank. The signal lamps, indicating &#39;&#39;&#39;&#39;nose up&#39;&#39;&#39;&#39;, &#39;&#39;&#39;&#39;nose down&#39;&#39;&#39;&#39;, &#39;&#39;&#39;&#39;left wing down&#39;&#39;&#39;&#39; and &#39;&#39;&#39;&#39;right wing down&#39;&#39;&#39;&#39; are in circuits energized by a first switching means controlled by the relative rotational position of the inner and outer gimbals of the instrument for sensing departure beyond reasonable safety limits in one direction or the other in the pitch axis, i.e., either &#39;&#39;&#39;&#39;nose up&#39;&#39;&#39;&#39; or &#39;&#39;&#39;&#39;nose down&#39;&#39;&#39;&#39; flight, and a second switch means controlled by the relative rotational position of the outer gimbal and the instrument casing for sensing departure beyond reasonable limits in the roll axis, i.e., either &#39;&#39;&#39;&#39;left wing down&#39;&#39;&#39;&#39; or &#39;&#39;&#39;&#39;right wing down&#39;&#39;&#39;&#39; flight.

Unite Sttes Hernandez, ,1 r.

ate

[ 1 Mar. 27, 1973 [75] Inventor: Ralph Hernandez, Jr., Miami, Fla.

[73] Assignee: Aircraft Instruments, Inc., Miami Beach, Fla.

22 Filed: Apr. 3, 1969 211 App]. No.: 813,252

[52] 11.8. Cl ..340/27, 313/204 C, 74/522 [51] Int. Cl. ..G08g 5/00 [58]Field of Search .33/204.2, 226; 340/27 AT, 282; 74/5.22, 5.6, 5.41, 5.4;244/79, 335/151;

ZOO/61.45, 61.52, 61.46; 343/108, 112

[56] References Cited UNITED STATES PATENTS 1,856,436 5/1932 Schueller..'..33/204 2,663,008 12/1953 McEwan ..33/204 2,883,863 4/1959 Karsten..74/5.22 3,307,413 3/1967 DeBoer et al. ..74/5.6 3,339,864 9/1967Whitsen ..244/1 1,456,744 5/1923 Tanner ..74/5.4 1,618,570 2/1927Chessin ..74/78 1,906,719 5/1933 Richter ..74/5.41 2,482,504 9/1949Pennington ..340/27 2,304,061 12/1942 Little 335/151 2,745,091 5/1956Leffler ..340/27 2,911,618 11/1959 Servanty ..340/282 FOREIGN PATENTS ORAPPLICATIONS 1,134,273 11/1968 Great Britain 737,236 9/1955 GreatBritain .33/204 Primary Examiner- Ralph D. Blakeslee Att0rney-Ernest H.Schmidt [57] ABSTRACT A combination gyrohorizon instrument for aircraftwhich 'visually indicates in addition to the dial display presentationof the instrument, by means of signal lamps appropriately placed withrespect to the instrument dial, departures from straight and levelflight that exceed reasonable limits of pitch and bank. The signallamps, indicating nose up, nose down, left wing down and right wing downare in circuits energized by a first switching means controlled by therelative rotational position of the inner and outer gimbals of theinstrument for sensing departure beyond reasonable safety limits in onedirection or the other in the pitch axis, i.e., either nose up" or nosedown flight, and a second switch means controlled by the relativerotational position of the outer gimbal and the instrument casing forsensing departure beyond reasonable limits in the roll axis, i.e.,either left wing down" or right wing down flight.

2 Claims, 10 Drawing Figures Patented March 27, 1973 3,723,963

5 Sheets-Sheet 1 BY WM ATTORNEY Patented March 27, 1973 3 Sheets-Sheet 2m m &

INVENTOR. FQLPH HE R AJHNDE Z (JR.

4 TTOfiF/UE).

III

Patented March 27, 1973 5 Sheets-Sheet 5 INVENTOR. RALPH HERA/1 7N052(/IQ,

BY W I m'mM/Ex AIRCRAFT GYROIIDRIZON INDICATOR WITH SIGNAL LAMPPOSITIONAL ATTITUDE INDICATING MEANS This invention relates to flightcontrol instruments and is directed particularly to improvements ingyrohorizon or artificial horizon instruments whereby the positionalattitude of the aircraft when departing beyond predetermined acceptablelimits from straight and level flight, in addition to being displayedinthe usual manner on the instrument dial, is indicated by the selectiveenergization of appropriately located signal lamps in the instrumentpanel. This invention is a continuation-in-part of applicants patentapplication Ser. No. 704,844, Filed Feb. 12, 1968 now abandoned, whereinthere is described a device utilizing pendulumactuated switchescontrolling the energization of nose up", nose down, left wing down andright wing down signal lamp warning of corresponding departures of theaircraft from straight and level flight.

Presently, aircraft are equipped with various flight positional controlinstruments, the simplest of which are the basic turn and bank indicatorand the artificial horizon instrument, readings of which are used by thepilot as an aid in determining aircraft attitude and control needed toset up and recover from a maneuver. While such instruments can beinspected casually from time to time under flight conditions, it is wellknown that blind flying without the use of such instruments willinvariably lead to disaster because of the inability of the senses toproperly interpret the sensations of flight without visual contact withthe ground or horizon. Since in blind flying situations theinexperienced pilot, especially, will find it difficult to reconcile hisphysical feelings of aircraft attitude and motion with actual conditionsas shown by the instruments,

close observation and reliance on the instruments is required for him toachieve and maintain normal and controlled flight. Ordinarily, since thepilot flying into instrument or blind flying weather conditions willalready be in an anxious state of mind, the difficulty of maintainingsuch close concentration while at the same time making proper correctivecontrol to achieve the controlled flight, is too often beyond thecapability of the inexperienced pilot, whereupon complete loss ofcontrol can occur within a matter of minutes.

It is, accordingly, the principal object of this invention to provide,in combination with a gyrohorizon instrument, a simple and effectiveflight control co-ordination signal means, in addition to the dialpresentation of the instrument itself, in the form of a group of signallamps indicating nose up", nose down, right wing up and right wing down,aircraft position for signaling positional attitude and changes inpositional attitude under instrument flight conditions. The signal lampsare so placed in the instrument panel with respect to their associatedgyrohorizon instrument that they can be observed and understood withoutthe necessity of the pilot looking directly at them, whereby hisattention can be directed to other instruments or apparatus needed toachieve and maintain normal flight under instrument conditions. Sincethe signal lamps operate instantly, immediate corrective control can beeffective by the pilot without critical observation of the instruments.Overcontrol will be reflected immediately by operation of the indicatorlamps, so that proper control can readily be achieved without closeconcentration on the instruments.

A more particular object is to provide a combination gyrohorizoninstrument of the character described wherein the signal lamp switchingis effected by the provision of a first slip ring switch meanscontrolled by the relative rotational position of the inner gimbal andthe outer gimbal for sensing departure beyond reasonable limits in thepitch axis, and a second slip ring means controlled by the relativerotational position of the outer gimbal and the instrument casing forsensing departure beyond reasonable limits in the roll axis.

Yet another object is to provide a combination gyrohorizon instrument ofthe above nature wherein, instead of using slip ringsmagnetically-actuated rocker switches are utilized, therebysubstantially eliminating frictional drag between the gimbals andbetween the outer gimbal and the casing, while at the same timeminimizing wear and improving reliability and durability.

Yet another object of the invention is to provide a flight controlindicator of the character described which will not present a warningindication under normal flight conditions, but will indicate abnormal ordangerous maneuvers.

Other objects, features and advantages of the invention will be apparentfrom the following description when read with reference to theaccompanying drawings.

Referring now in detail to the drawings, wherein like reference numeralsdenote corresponding parts throughout the several views:

FIG. 1 is a partial view of an aircraft instrument panel illustrating agyrohorizon indicator modified in accordance with the invention, andshown in association with horizontal and vertical warning signal lights;

FIG. 2 illustrates, in side elevation and shown separately, a typicalgyrohorizon indicator or artificial horizon instrument embodying thepresent invention;

FIG. 3 is a rear end view, on an enlarged scale, of the gyrohorizonindicator shown in FIG. 1, with the end cover removed to show the slipring and brush mechanism;

FIG. 4 is a vertical cross-sectional view of the modified gyrohorizonindicator, taken along the line 4-4 of FIG. 1 in the direction of thearrows and on an enlarged scale;

FIG. 5 is a fragmentary view, on an enlarged scale and withportionsbroken away, of the rear end spindle portion of the outer gimbal,illustrating constructional details of the slip ring assembly;

modified form of the gyrohorizon indicator shown in,

FIG. 8, with the end cover removed to show the magnetic switch and slipring mechanism; and

FIG. 10 is a plan view, taken along the plane indicated by the line10-10 in FIG. 8, illustrating details of the magnetic switchingmechanism operating between the inner and outer gimbals.

In brief, my invention provides, in combination with and as an adjunctto the usual attitude gyro instrument in an aircraft instrument panel P,visual indication of departure from reasonable limits in aircraftattitude with respect to both pitch and roll. Preferably, as illustratedin FIG. 1, nose up and nose down signal lamps l1 and 12, representativeof deviations from pitch axis attitude will be located centrally aboveand below, respectively, the gyrohorizon indicator instrument 10, andthe left wing down" and right wing down signal lamps 13, 14,representative of deviations from roll axis attitude, will be mounted tothe left and to the right respectively, of said instrument, whereat saidsignal lamps will be best adapted to alert the pilot that correctivemeasures should be taken to maintain level flight.

Since the construction and operation of artificial horizon gyros of thetype herein modified in carrying out the present invention is wellknown, only so much of the construction of the instrument as is deemednecessary is illustrated and described herein. Thus, as illustrated inFIGS. 1 and 2, the artificial horizon gyro or gyrohorizon indicatorinstrument 10 comprises an instrument casing in the face of which ahorizon bar 16 controlled by the gyro mechanism represents the horizon,and a small figure 17, representative of the airplane, in the center ofthe dial represents the aircraft. The position of the airplane symbolrelative to the horizon bar indicates the actual position of theaircraft with respect to the natural horizon. Referring to FIG. 4, thegyro mechanism, by means of which the horizon bar 16 is indicative ofthe natural horizon, comprises an inner gimbal 18, within which the gyrorotor is contained with its spin axis maintained in a horizontalposition, and an outer gimbal 19 journalled for axial rotation withinthe instrument casing 15 and having a rear outer gimbal spindle shaft 20extending through a rear end portion of said casing and into an airflowchamber 21. The airflow chamber 21 in the modification of the instrumentin accordance with the present invention is somewhat extended in axiallength by the provision of a cylindrical spacer sleeve 22 between therear end of the instrument casing 15 and the usual airflow chamber endplate 23, to provide space for added slip ring and brush mechanism as ishereinafter described.

Referring now to FIGS. 3 through 6 in the drawings, it will be seen thatthe outer gimbal spindle shaft 20 is fitted with a non-conductive,cylindrical slip ring disc 24, said slip ring disc being formed with areduceddiameter flange portion 24a fitted with a radially-extending setscrew 24b by means of which said disc is adjustably secured in place.The slip ring disc 24 has imbedded in its outer periphery asemi-circular, arcuate conductor element 25, slightly less than 180circular degrees in extent. Brush means is provided for closing theelectrical energizing circuit including the left wing down" signal lamp13 and the right wing down" signal lamp 14 under correspondingconditions as sensed by the gyrohorizon indicator instrument 10. To thisend, as is best illustrated in FIG. 3, a pair of laterally-opposed,electrically non-conductive brush support plates 26, 27, carryingconductive brush support posts 28, 29, respectively, are provided, saidbrush support posts being fitted with spring wire brushes 30, 31,respectively, which as illustrated in FIG. 6, resiliently contact theouter periphery of the slip ring disc 24 at positions just beyond theouter ends of the associated arcuate conductor element 25 when theaircraft is in level flight, irrespective of nose up or nose downattitude of the aircraft, as sensed by the gyrohorizon indicatorinstrument 10. The brush support plate 26 also carries a brush supportpost 32 fitted with a spring wire brush member 33, normally contactingthe arcuate conductor element 25 at a central position therealong. Asmeans for adjusting the distance between the outer ends of the arcuateconductor element 25 and the contact points of the spring wire brushes30, 31 under level flight conditions, the brush support plates 26, 27are provided with arcuate slots 34, 35, respectively, by means of whichsaid support plates can be adjustably secured against the outer end ofthe instrument casing by the use of respective machine screws 36 and 37.

Means is also provided for closing the electrical energizing circuitsincluding the nose up signal lamp l1 and the nose down signal lamp 12under corresponding aircraft attitude positions exceeding predeterminedlimits of deviation in the pitch axis as sensed by the modifiedgyrohorizon indicator instrument 10. To this end, as illustrated in FIG.4, the inner gimbal journal shaft 38 at one side of the inner gimbal 18is fitted with a relative fixed, non-conductive cylindrical slip ringdisc 39 imbedded in the outer periphery of which is a semi-circulararcuate conductor element 40 of somewhat less than circular degrees inextent. A pair of laterally opposed, arcuate, non-conductive supportmembers 41, 42 are provided in concentric relation with respect to theslip ring disc 39 and adjustably secured in place by means of clampplates 43, 44 against an inner wall portion of the outer gimbal 19, saidclamp plates being secured by machine screws 45. Spacers 46 between theclamp plates 43, 44 provide concentric arcuate inner edges 47 forlocating the outer peripheries of said support members in their circularadjustment upon being clamped in place. The arcuate support members 41,42 carry conductive support posts 48, 49, respectively, which, in turn,support spring wire contact brushes 50, 51, respectively, the outer endsof which are slightly spaced from the outer ends of the arcuateconductor element 40 when the aircraft is in level attitude in the pitchaxis irrespective of roll or left-wing down or right-wing down" attitudeof the aircraft as sensed by the hyrohorizon indicator instrument 10.

The clamp plate 44 carries a first support post 52 having securedthereto a common wire brush member 53 in contact with the arcuateconductor element 40 at a central position therealong. The clamp plate44 also carries a second support post 52a, in electrical circuit withthe brush 53 through said metal clamp plate 44. Conductors 54, 55 and 56connected, respectively, to the support posts 48, 49 and 52a, extendthrough an axial opening 57 in the outer gimbal spindle shaft 20 (SeeFIG. 5) press-fitted in the outer end of which is a non-conductivetubular sleeve 58. Axially-spaced along the non-conductive sleeve 58 arecircular slip rings 59, 60 and 61 which are electrically connected, fromthe inside, with conductors 54, 55 and 56, respectively. Brush means isprovided for making electrical contact with the slip rings 59, 60 and61. To this end, as is best illustrated in FIGS. 4 and 5, there isprovided a metal support plate 62 secured in spaced relation against theouter end of the instrument casing by means of machine screws 63extending through said support plate and spacer sleeves 64. Inner andouter non-conductive clamp members 65, 66, respectively, secured inplace against the outside of the support plate 62 by means of machinescrews 67, fix therebetween the inner ends of wire brush members 68, 69and 70, the outer ends of which are in sliding contact with the sliprings 59, 60 and 61, respectively.

Referring now to FIG. 7 and considering the electrical wiring of thedevice, the same comprises a ground circuit including a common groundconductor 71 connected to one terminal of the aircraft battery 72. Thepositive or hot terminal of the battery 72 connects to the rotary switcharm of a three-position switch 73. In the position of the switch 73illustrated in FIG. 7, being the test position, contact is made withconductor 80, leading to a push-button test switch for testing thesignal lamps 11, 12, 13 and 14, simultaneously, as is hereinafterdescribed. With the rotary switch 73 moved to the left or on position asillustrated in FIGS. 1 and 7, contact is made through the battery 72with the conductor 75 which, in turn, is connected with the commonspring wire brushes 33 and 53. The remaining energization terminals ofthe signal lamps 11, 12 connect through respectiveconductors 76, 77 towire contact brushes 50, 51, and extend to terminate at the push buttontest switch 81. The remaining energization terminals of the signal lamps13, 14 connect through conductors 78 and 79, respectively, to the springwire contact brushes 30 and 31, and extend further to terminate at thepush button test switch 81. In operation the rotary switch will first beturned from the off position, being the position to the left asrepresented in FIGS. 1 and 7, to the central or test position. The pushbutton test switch will then be actuated to simultaneously energize thesignal lamps 11, 12, 13 and 4 through hot" conductor 80. After theoperability of the signal lamps has thus been determined, the switch arm73 will be turned to the left to render the arcuate conductor elements25 and 40 hot whereupon they will serve to energize one or the other oftheir pair of associated signal lamps upon departure from straight andlevel flight in either the pitch or the roll axis, as has beenhereinabove described..As indicated in FIGS. 1 and 4, the internalcircuitry of the instrument connects with the external circuitcomponents through a flexible cable 82 which extends through an openingin the cylindrical spacer sleeve 22 of said instrument.

Referring now to FIGS. 8 through 10, wherein there is illustrated amodified form of the invention utilizing magnetic switches operatingbetween the inner and outer gimbals, it will be seen that the outergimbal spindle shaft 20 is fitted with a non-conductive, non-magneticcircular disc 83 having a reduced diameter flange portion 84 providedwith a set screw (not illustrated) for adjustable securement. The disc83 has affixed thereto, at the inside and near the outer peripherythereof, a small circular permanent magnet 85 which will normally bepositioned centrally and in spaced relation between a pair of opposedferromagnetic, elongated switch rocker members 86, 87, said switchrocker members being rockably supported with respect to the rear wallportion of the casing 15 by pivot pins 88, 89. Leaf springs 90, 91associated with the respective rocker members 86, 87 normallyresiliently urge said rocker members so that their opposed inner endsare in down position, whereat their respective movable switch contacts92, 93 will be in open-circuit position with respect to their associatedfixed contacts 94, 95. It will thus be understood that when the smallmagnet is in its central position representative of level flight, theassociated switches will remain open circuited, regardless of nose-up ornose-down attitude of the aircraft as sensed by the gyrohorizoninstrument 10. When the magnet moves sufficiently to one side or theother it will attract the corresponding rocker switch member 86 or 87 toclose its associated switch as described above, which switch, it will beunderstood, will be in circuit with the corresponding signal lamp 13 or14 to appropriately signal deviation from normal flight in the rollaxis.

Referring to FIG. 10 of the modified form on the invention, it will beseen that magnetically operated switches are also provided for closingthe electrical energizing circuits including the nose-up signal lamp 11and the nose-down signal lamp 12 under corresponding aircraft attitudepositions as sensed by the gyrohorizonjndicator instrument 10. To thisend, the inner gimbal journal shaft 38 at one side of the inner gimbal18 is fitted with a circular, non-magnetic disc 96 having affixedthereto, at the outside and near its outer periphery, a small, circularpermanent magnet 97,

which will normally be positioned centrally and in spaced relationbetween a pair of opposed ferromagnetic, elongated switch rocker members98, 99, said switch rocker members being rockably supported with respectto an inner wall portion of the outer gimbal 19 by pivot pins 100, 101.Leaf springs 102 and 103 associated with the respective rocker members98, 99 normally resiliently urge said rocker members so that theiropposed inner ends are in down position, whereat their respectivemovable switch contacts 104, will be in open-circuit position withrespect to their associated fixed contacts 106, 107. It will thus beunderstood that when the small magnet 97 is in its central position, theassociated switches will remain open-circuited, regardless of left-wingdown or right-wing down" attitude of the 1 aircraft as sensed by thegyrohorizon instrument 10. When the magnet 97 moves sufficiently to oneside or the other, it will attract the corresponding rocker switchmember 98 or 99 to close its associated switch as described above, whichswitch, it will be understood, will be in circuit with the correspondingsignal lamp 13 M14 to appropriately signal deviation from normal flightin the pitch axis. In the above described'embodimen't of the inventionillustrated in FIGS 8 through 10, it will be understood that the pairsof rocker member contacts 92, 93, 104 and 105 will be connected incommon, as in parallel with the hot conductor 75 illustrated in FIG. 7,in lieu of the arcuate conductor elements 25 and 40 of the firstembodiment of the invention, and that the electrical circuitry willotherwise be the same as is illustrated in FIG. 7.

What I claim as new and desire to secure by Letters Patent is:

1. A device for signalling departure beyond predetermined limits fromstraight and level flight as indicated by a gyrohorizon instrumenthaving a casing, an outer gimbal pivotally journalled within the casing,being determinative of deviation of an aircraft in the roll axis, and aninner gimbal, pivotally journalled within the outer gimbal about an axisperpendicular to the journal axis of the outer gimbal, the relativerotational position thereof, with respect to the outer gimbal, beingdeterminative of deviation of an aircraft in the pitch axis; thecombination comprising, a first pair of signal lamps indicating, whenenergized, nose up and nose down" aircraft positional attitude,respectively, in the pitch axis, a second pair of signal lamps forindicating, when energized, left wing down" and right wing down aircraftpositional attitude, respectively, in the roll axis, a first meanscontrolled by the relative position of said inner gimbal with respect tosaid outer gimbal for selectively energizing one or the other of saidfirst signal lamps in accordance with corresponding nose up and nosedown aircraft positional attitude, and a second means controlled by therelative position of said outer gimbal with respect to said casing forselectively energizing one or the other of said second pair of signallamps in accordance with corresponding left wing down" and right wingdown aircraft positional attitude, said first pair of signal lamps beingmounted directly above and below the indicating dial of the gyrohorizoninstrument in an aircraft panel, and said second pair of signal lampsbeing mounted directly at each side of said instrument dial, therebyserving as a warning that the aircraft has departed from safe flightparameters, and thereby also serving to indicate the direction ofaircraft deviation and whether such deviation is in pitch or in roll orboth in pitch and roll.

2. A device for signalling departure beyond predetermined limits fromstraight and level flight as defined in claim 1 wherein said firstenergizing means comprises a first energizing circuit for each of saidfirst pair of signal lamps, normally open-circuit first switch means ineach of said first energizing circuits, means controlled by the relativemovement of said inner gimbal with respect to said outer gimbal-in onedirection or the other to selectively actuate said first switch means,second energizing circuits for each of said second pair of signal lamps,normally open-circuit second switch means in each of said secondenergizing circuits, and means controlled by the relative movement ofsaid outer gimbal with respect to said casing in one direction or theother to selectively actuate said second switch means.

1. A device for signalling departure beyond predetermined limits fromstraight and level flight as indicated by a gyrohorizon instrumenthaving a casing, an outer gimbal pivotally journalled within the casing,being determinative of deviation of an aircraft in the roll axis, and aninner gimbal, pivotally journalled within the outer gimbal about an axisperpendicular to the journal axis of the outer gimbal, the relativerotational position thereof, with respect to the outer gimbal, beingdeterminative of deviation of an aircraft in the pitch axis; thecombination comprising, a first pair of signal lamps indicating, whenenergized, ''''nose up'''' and ''''nose down'''' aircraft positionalattitude, respectively, in the pitch axis, a second pair of signal lampsfor indicating, when energized, ''''left wing down'''' and ''''rightwing down'''' aircraft positional attitude, respectively, in the rollaxis, a first means controlled by the relative position of said innergimbal with respect to said outer gimbal for selectively energizing oneor the other of said first signal lamps in accordance with corresponding''''nose up'''' and ''''nose down'''' aircraft positional attitude, anda second means controlled by the relative position of said outer gimbalwith respect to said casing for selectively energizing one or the otherof said second pair of signal lamps in accordance with corresponding''''left wing down'''' and ''''right wing down'''' Aircraft positionalattitude, said first pair of signal lamps being mounted directly aboveand below the indicating dial of the gyrohorizon instrument in anaircraft panel, and said second pair of signal lamps being mounteddirectly at each side of said instrument dial, thereby serving as awarning that the aircraft has departed from safe flight parameters, andthereby also serving to indicate the direction of aircraft deviation andwhether such deviation is in pitch or in roll or both in pitch and roll.2. A device for signalling departure beyond predetermined limits fromstraight and level flight as defined in claim 1 wherein said firstenergizing means comprises a first energizing circuit for each of saidfirst pair of signal lamps, normally open-circuit first switch means ineach of said first energizing circuits, means controlled by the relativemovement of said inner gimbal with respect to said outer gimbal in onedirection or the other to selectively actuate said first switch means,second energizing circuits for each of said second pair of signal lamps,normally open-circuit second switch means in each of said secondenergizing circuits, and means controlled by the relative movement ofsaid outer gimbal with respect to said casing in one direction or theother to selectively actuate said second switch means.